Effects of Roll Gap, Kernel Shape, and Moisture on Wheat Breakage Modeled Using the Double Normalized Kumaraswamy Breakage Function

Abstract

Flour milling separates endosperm from bran through repeated roller milling and sifting, in which the size distribution of particles produced by the initial breakage of the wheat kernels critically affects the process. The double normalized Kumaraswamy breakage function (DNKBF), previously developed to describe wheat breakage during roller milling, was extended to refine the modeling of the effect of roll gap on breakage. The DNKBF describes two populations of particles arising from roller milling of wheat, a narrow peak of mid‐sized particles and a wider distribution of both small and very large particles. A new dataset was obtained from milling a set of wheat samples bred to give a range of shapes by cross‐breeding a conventional wheat, Cappelle, with an almost spherical wheat, Triticum sphaerococcum. A residual analysis showed a statistically significant effect of kernel shape on breakage using this new dataset. This analysis supports earlier suggestions that more elongated kernels break to give slightly larger particles than more spherical kernels of equivalent hardness, because of the relatively greater bran content of elongated kernels. The extended DNKBF was also used to model effects of moisture content, showing a distinct disjunction at around 16% moisture that aligns with commercial practice for wheat milling.

Modeling First Break Milling of Debranned Wheat Using the Double Normalized Kumaraswamy Breakage Function

“…7B). Previous work similarly found that soft wheats under D-D were the least well behaved in terms of the adequacy of the DNKBF (Campbell et al 2012), particularly in accounting for effects of roll gap (Fuh et al 2014). Overall, however, it could be concluded that the DNKBF described the experimental data well and allowed effects of debranning on first break milling of wheat to be distinguished and quantified.…”

“…Previous work concluded that, for whole wheats, the relationship between milling ratio and output particle size was approximately a square root relationship (a = 0.5) under D-D and slightly less than a square root relationship (a = 0.4) under S-S for a wide range of wheat hardnesses (Campbell et al 2012;Fuh et al 2014). In so doing, it allows the relationship between the milling ratio and the output particle size to be quantified.…”

“…In so doing, it allows the relationship between the milling ratio and the output particle size to be quantified. Previous work concluded that, for whole wheats, the relationship between milling ratio and output particle size was approximately a square root relationship (a = 0.5) under D-D and slightly less than a square root relationship (a = 0.4) under S-S for a wide range of wheat hardnesses (Campbell et al 2012;Fuh et al 2014). The difference in a indicates that milling is more sensitive to roll gap under D-D than S-S. Figure 2 shows the best fit value of a at different debranning times for Mallacca and Consort wheat milled under S-S and D-D dispositions.…”

“…Knowing that, during roller milling of wheat, the bran tends to stay as large particles and the endosperm forms small particles, it is tempting to relate these two apparent breakage types to bran and endosperm breakage, respectively, but it is necessary to be cautious in attributing a physical meaning to a convenient mathematical description (Campbell et al 2012). Fuh et al (2014) extended the DNKBF equation to allow for more accurate prediction of the effect of roll gap on breakage, at the cost of a single extra parameter. Although the extended form of the DNKBF introduced by Fuh et al (2014) combined greater accuracy with relative simplicity, in the current work it was found that the extra parameter introduced instability (results not shown).…”

μCT trait analysis reveals morphometric differences between domesticated temperate small grain cereals and their wild relatives

“…Cultivation methods, such as tillage, are also thought to have contributed to grain size increases as bigger seeds could tolerate sowing at increased depths and therefore be selected for indirectly (Zohary et al, 2012). In addition, food processing methods may have led to selection for grains with bigger endosperm as they would be easier and more profitable to mill (Fuh et al, 2014). Alternatively, larger grains could have arisen via pleiotropic effects or genetic linkage and driven by selection that favoured larger organs and plants (Kluyver et al, 2017).…”